There are usually two phases to our trips -- the "mileage" part and the fun part. So, for example, when we go to Utah from Southern Calif., we streak across the desert for 450 miles in one day, in order to get to the fun part.
Then things slow down -- we camp for a few days in one spot, move a couple hundred miles to the next spot, etc.
When it comes time to get back home, we shift back into overdrive and streak for home.
This pattern could be a result of geography -- Southern Calif is bordered by desert on the north and east, and DW is not a desert person.